ORBITAL SINE CURVES AND HUMAN CONCEPTIONS IN THE UNITED-STATES-OF-AMERICA

The annual pattern of human conceptions in the United States of Americ a for the eleven year interval from Jan., 1967 thru Dec., 1976 were an alyzed with a regression technique. Initially an orbital model, consis ting of two sine curves, one with an period of one year that peaked in June and the other with a semiannual period that peaked in March and September, was fitted to the monthly values of conceptions for the 132 months of the 11 year interval. Separate analyses were conducted for each state. An analysis of variance indicated that the orbital model w as a significant predictor for all states except Montana and North Dak ota, Inspection of the residuals revealed systematic trends that were accounted for by adding other predictor variables. A latitudinal trend in the percentage of the variance accounted for by the orbital model was established, as well as a latitudinal trend in the residuals that indicated systematic changes with latitude in April and July values. T he annual pattern of ''mood swings'' in patients with seasonal affecti ve disorders was found to enter the regression equation at higher lati tudes. The previously established latitudinal trend in seasonal affect ive disorder and in multiple sclerosis were discussed and compared to the latitudinal trend in conceptions.